#define  _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
void  Bubble(char* p1)
{
	int i = 0;
	int j = 0;
	int ct = 0;
	while (p1[i] != 0)
	{
		ct++;
		i++;
	}
	for (i = 0; i < ct - 1; i++)
	{
		for (j = 0; j < ct - i - 1; j++)
		{
			if (p1[j] > p1[j + 1])
			{
				char tmp = p1[j+1];
				p1[j + 1] = p1[j];
				p1[j] = tmp;
			}
		}
	}
}
char* str_bin(char* str1, char* str2)
{
	char* p1 = str1;
	while (*str1 != 0)
	{
		str1++;
	}
	while (*str2 != 0)
	{
		*str1 = *str2;
		str1++;
		str2++;
	}
	Bubble(p1);

	return p1;
}
int main()
{
	char arr1[200] = { 0 };
	char arr2[100] = { 0 };
	scanf("%s", arr1);
	scanf("%s", arr2);
	char* p = str_bin(arr1, arr2);
	printf("%s", p);
	return 0;
}